This invention relates generally to couplings for tubing and particularly to couplings made of elements that press against the interior walls of tubing sections in order to keep them coupled.
It is frequently desirable to couple tubular sections with an internal element that keeps the exterior of the tubular sections free of protruding fittings. One approach is to have two separable elements that span the sections to be joined. The elements are arranged to engage the interior walls of the sections by the action of threaded members that force the separable elements apart. Such couplings are shown, for example, in U.S. Pat. application Nos. 2,850,304 and 3,484,830. The couplings are sometimes difficult to use and install, however. The components of the coupling may also move relative to each other during installation. The location of the coupling itself within the tubing may become indeterminate.
It is an object of this invention to provide a coupling for tubing sections that is easy to use and locate in the tubing sections. It is another object to provide a coupling that has one end for semi-permanent installation in one tubing section and another end for easy use so that the tubing sections can be assembled and dissassembled rapidly.